Here is a good example of allopathic medicine trying to catch up to alternative medicine.   For years, it has been known by many alternative healers and researchers that the body's need for vitamin D could lead to all manner of diseases and problems, just as other deficiciences can.  But, it is not until some sanctioned clinical study is paid for that we the public get to find out. How many get sick and die in the meantime?  It just proves we have to be PRO ACTIVE in seeking our health these days.  No doctor cares about your health as much as you do. You have to go out and look for information if you want to stay healthy and fit.  It is there but it takes work to sift the wheat  from the chaff.

http://www.webmd.com/heart-disease/news/20080811/low-level-of-vitamin-d-ups-death-risk

PS there are many more benefits that elaborated in this article. The Google search engine is a great tool.  Hint:  the type of vitamin d is very important, i.e. natural. Too much of the wrong kind can cause problems too.